Introduction

Dilated Cardiomyopathy (DCM) is a disease of the heart muscle characterized by enlargement and dilation of one or both of the ventricles along with impaired contractility defined as left ventricular ejection fraction (LVEF) less than 40%. By definition, patients have systolic dysfunction and may or may not have overt symptoms of heart failure. This disease process can be classified as either primary or secondary DCM. Primary DCM is considered idiopathic and the diagnosis can only be made after excluding secondary causes.[1][2][3]

Etiology

The most common etiology of dilated cardiomyopathy (DCM) is idiopathic and without an identifiable cause. DCM can have a familial or genetic predisposition although these cases are usually classified under idiopathic if no clear genetic link is identified. DCM has been associated with mutations in genes for Desmin (cytoskeletal), Lamin C (nuclear membrane), or Myosin (contractile proteins). The secondary causes include infectious myocarditis (e.g., viral, Chagas disease, Lyme disease), ischemic disease, hypertension, medication-induced (e.g., Anthracyclines), alcohol abuse, human immunodeficiency virus (HIV), peripartum cardiomyopathy, or infiltrative disease. Ischemic cardiomyopathy caused by coronary artery disease (CAD) is the most common cause of congestive heart failure. However, ischemic cardiomyopathy is classified as its own disease entity and is only described as a cause of DCM in occult disease in patients without known CAD. Stress cardiomyopathy, also known as Takotsubo cardiomyopathy or Broken heart syndrome, is a relatively uncommon but increasingly reported cause. However, it is often classified as its own entity separate from primary DCM. It is characterized by transient ballooning of the left ventricular (LV) apex typically following a severe psychological or physiological stress that is believed to be secondary to intense catecholamine surge.[4]

Epidemiology

DCM is more commonly seen in men than in women. Its prevalence in the general population is estimated at 36 cases per 100,000. DCM accounts for 10,000 deaths and 46,000 hospitalizations in the United States annually. These figures may underestimate the true prevalence because many patients are asymptomatic and, therefore, undiagnosed despite LV dysfunction. [5][2]

Pathophysiology

Many cases of dilated cardiomyopathy (DCM) are due to idiopathic etiology. But, it also can arise from various myocardial insults. Enlargement of the ventricles can either be secondary to LV failure or secondary to a primary cardiomyopathic process and can be associated with both systolic and diastolic dysfunction. Reduction in systolic function is believed to be caused by myocardial remodeling that results in an increase in both end-systolic and end-diastolic volumes. Histologic examination or the myocardium typically shows nonspecific changes of fibrosis and hypertrophy. It also reveals myocardial injury with a marked infiltrate by inflammatory cells. [6]

History and Physical

The majority of cases of dilated cardiomyopathy (DCM) present between the ages of 20 and 60; however, DCM can be seen in children or the elderly. A large number of patients with DCM may have a long latent period where they are clinically asymptomatic. When symptoms do arise, they are the result of LV systolic dysfunction. In addition to a focused cardiac history and examination, a more thorough evaluation is recommended to identify any systemic disease or secondary causes. Classic symptoms include paroxysmal nocturnal dyspnea, orthopnea, leg swelling, and shortness of breath. Nonspecific symptoms of fatigue, malaise, and weakness also can be present. More severe cases can present with thromboembolic complications, conduction disturbances, arrhythmias or even sudden cardiac death. Physical examination findings are largely not specific to other causes of cardiomyopathy and consist of typical findings seen with congestive heart failure. Findings include crackles in the lung fields, elevated jugular venous pressures, peripheral edema, and an S3 gallop. Classically, the point of maximum impulse or PMI is displaced laterally. Tricuspid or mitral regurgitation murmurs are not uncommon as a result of ventricular enlargement and annular dilation.

Evaluation

An evaluation for secondary causes of dilated cardiomyopathy (DCM) always should be pursued prior to making the diagnosis of idiopathic DCM. Workup is focused on identifying any possible reversible causes. Recommended laboratory testing includes thyroid function tests, HIV serology, electrolytes, and iron studies (to rule out hemochromatosis). Urine toxicology screen and alcohol level can be checked when substance abuse is suspected. In certain familial cases, genetic testing should be considered. Serum B-type natriuretic peptide (BNP) levels may be obtained in cases where the diagnosis is unclear. Chest X-ray may show cardiomegaly and evidence of pulmonary effusions and venous congestion. Electrocardiogram (EKG) may show nonspecific ST segment and T wave abnormalities. Echocardiography is crucial in making the diagnosis of DCM and provides an objective assessment of ventricular size, function, and any associated valvular abnormalities. Echocardiography also can identify the presence of a mural thrombus. Coronary angiography should be performed in those without a known history of CAD to further define coronary anatomy and rule out occult ischemic disease as the cause of DCM. Very rarely, a myocardial biopsy is needed for evaluation of storage diseases or infiltrative causes when suspected. As mentioned, histologic findings of idiopathic DCM are nonspecific, and biopsy exposes patients to unnecessary risk.[7]

Treatment / Management

Besides treating any identifiable and reversible underlying causes, the management and treatment of Dilated Cardiomyopathy (DCM) are in concordance with the standard heart failure guidelines. In patients with an acute congestive heart failure exacerbation, intravenous loop diuretics are given to treat hypervolemia. Management of chronic and stable disease with oral diuretics often is needed to achieve a euvolemic state. Angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARB) have shown benefit in the treatment of heart failure with reduced ejection fraction and are recommended in patients with DCM. Aldosterone receptor blockade with spironolactone or eplerenone also is recommended in patients with New York Heart Association (NYHA) heart failure class II-IV and systolic dysfunction. Similarly, beta-blockade with carvedilol, bisoprolol, or long-acting metoprolol is recommended in all patients with heart failure with reduced ejection fraction without any contraindications. The addition of isosorbide dinitrate plus hydralazine also has shown to increase survival amongst those with advanced disease. Finally, patients with disease refractory to maximum medical therapy should be considered for cardiac transplantation and LVAD as a bridge or for "destination" therapy in those who are not candidates for transplantation. Implanted cardioverter defibrillators (ICD) for primary prevention of sudden cardiac death and cardiac resynchronization therapy (CRT) can be considered and are recommended by the heart failure guidelines.[8][9][10]

Differential Diagnosis

Cardiac tamponade

Acute pericarditis

Hypertrophic cardiomyopathy

Restrictive cardiomyopathy

Prognosis

Overall, the prognosis of patients with dilated cardiomyopathy is guarded. Most patients eventually end up with chronic heart failure. Many become candidates for a heart transplant or an assist device which also adds more morbidity. The progression to heart failure depends on the ejection fraction and cause of the disease. Almost 50% of patients are dead within 5 years. With optimal medical therapy, patients with mild CHF can have a reasonably good quality of life.

Complications

Congestive heart failure

Cerebrovascular accident

Valvular heart disease

Abnormal cardiac rhythms

Sudden cardiac death

Postoperative and Rehabilitation Care

All patients with dilated cardiomyopathy need intense education on the diet. Both salt and water restrictions are necessary to prevent symptoms. Patients should remain physically active or enroll in a cardiac rehab program. Regular cardiac rehabilitation can lower the mortality rate by 20%, relieve symptoms and reduce adverse cardiac events.

Consultations

Cardiac surgeon

Cardiologist

Critical care specialist

Dietitian

Deterrence and Patient Education

Pearls and Other Issues

Unlike the past when all patients with DCM were empirically treated with anticoagulation, today the guidelines recommend the use of anticoagulants only in patients with atrial fibrillation, prosthetic heart valves, or known mural thrombus.

When there is progressive end-stage heart failure despite maximal medical therapy and the prognosis is deemed poor, one may consider a heart transplant.

All patients with DCM must be educated on the disorder and the importance of dietary restrictions in sodium and water.

Patients with DCM should be referred for cardiac rehabilitation as this has been shown to reduce all cause mortality by 20-30% over 5 years, including improvement in symptoms.

Enhancing Healthcare Team Outcomes

Dilated cardiomyopathy is a progressive heart disorder with no cure. Eventually, most patients progress to heart failure and close to 50% are dead within five years. Today many treatments have been devised for the treatment of dilated cardiomyopathy, but for most of them, there is a lack of evidence to support their use. There is no longer any question that this disorder is best managed by an interprofessional team that specializes in heart disease. The three single most important factors that determine the prognosis are 1) diet, 2) medication compliance, and 3) an exercise program. The disorder should be risk stratified and managed accordingly.[11][12]

A dietitian or a nurse is vital because one of the best ways to prevent progression to heart failure is by restricting fluid and salt intake. The family must be told to weigh the patient and offer foods that are low in salt. The pharmacist must ensure that the patient remains compliant with the medications. There is ample evidence indicating that participating in an exercise program can reduce symptoms and lower all-cause mortality. If the patient is deemed to be a candidate for a heart transplant, the heart transplant team should be consulted early on.

Outcomes

The outcomes of patients with dilated cardiomyopathy depend on the cause, ejection fraction, and comorbidity. At least 50% are dead within five years, and many others go on to develop heart failure. Despite many treatments available, the majority remain experimental. In view of the lack of data on treatments, it is imperative that the education of the patient and family be done to ensure that they comply with fluid and salt restriction. [13][14]

Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

A 68-year-old female with dilated cardiomyopathy presents with dyspnea, leg swelling, and fatigue. Her vital signs are blood pressure 115/75 mmHg, pulse 98 and regular, and respirations 26. The exam shows jugular venous distention, a holosystolic III/VI murmur at the apex, crackles at both lung bases, and 2+/4 pedal edema. An echocardiogram shows enlargement of all chambers, biventricular systolic dysfunction, moderate pulmonary hypertension, ejection fraction of 20%, and severe mitral regurgitation. After diuresis, what is the best therapy for this patient?

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

A 56-year-old female with presents to the emergency department with a 6-hour history of sub-sternal chest pain and shortness of breath. Two days earlier, her husband passed away from colon cancer.
Cardiac examination shows a normal S1 and S2 without S3, S4, murmur, or rub. Lung examination is normal. Serum troponin T level is 1.5 ng/mL
Electrocardiogram shows ST elevation in anterior leads. Transthoracic echocardiogram is perform revealing apical ballooning of the left ventricle.Cardiac Catheterization shows no significant coronary artery disease.
What is the most accurate diagnosis?

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

A 45-year-old man with a history of dilated cardiomyopathy presents to the emergency department. His ejection fraction is still 15% despite maximum medical therapy for the last six months. His EKG shows no significant ST segment changes, pathologic Q waves, or T wave inversions. His QRS is 100. What is the appropriate next step in management?

Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Radiology Tech-Cardiac US. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Radiology Tech-Cardiac US, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Radiology Tech-Cardiac US, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Radiology Tech-Cardiac US. When it is time for the Radiology Tech-Cardiac US board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Radiology Tech-Cardiac US.